Boulder finds preventing sewer problems in flood challenging

City utility director: System held up 'remarkably well'

Travis Poland, of Quality Pipe Services, pumps ground water out of a sewer line at the Manhattan West Apartments on Sept. 18, in Boulder.
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JEREMY PAPASSO
)

When Guy Burgess bought his south Boulder home, he did his research and was careful to buy a home outside the 100-year floodplain. But like hundreds of other Boulder residents who also thought they were safe from flooding, he ended up with a basement full of sewage.

The damage to his home wasn't as bad as that experienced by many of his neighbors, but it left him wondering whether the city could do anything to make its wastewater infrastructure more flood-resistant.

"It's the hidden flood," Burgess said. "It's not as bad as getting your house crushed by a mudslide, but it's so widespread."

Boulder public works officials said the system held up remarkably well given the magnitude of the rain event. The vast majority of the pipes that make up the wastewater conveyance system are intact, meaning that service could be restored as soon as flood waters recede enough to relieve pressure on the system.

Jeff Arthur, director of public works for utilities for the city, said the department will look strategically to see if there are places where improvements are warranted, but it's hard to engineer a system for the kind of rain event that occurs once every 1,000 years.

"It's pretty remarkable," he said. "We had significant operational issues, but in terms of the integrity of the system, it held up remarkably well."

Sewer backups were so widespread in Boulder because much of the sanitary system became pressurized during the storm. The sanitary sewers aren't meant to convey storm water, but as the ground filled with water, it found every crack and weakness in the system and forced its way in. Water running over the streets also got into the sewers through manhole covers. In some locations, such as Bear Creek and Table Mesa Drive, the water forced off the manhole cover, and the creek flowed directly into the sanitary sewer system.

The volume of flood water in the system could be measured at the wastewater treatment plant. It normally treats a little less than 12 million gallons a day. After the floods, it was treating 50 million gallons a day.

It took more than a week for water to subside enough for sewer service to return to normal for many parts of Boulder.

However, Arthur said, when the water subsided, they found that most of the system was intact. Berms designed to protect the low-lying wastewater treatment plant held. Flood waters threatened but did not take out the main pipe flowing into the treatment plant.

Only one area -- Spring Valley Road in north Boulder -- saw sewer pipes destroyed by flood water. Crews are pumping around the broken pipes and working to restore full service there, Arthur said.

"An event of this scale, we're very fortunate we didn't have more significant damage or destruction of components," Arthur said.

Weighing costs against frequency

Paul Bizier, president-elect of the Environmental and Water Resource Institute for the American Society of Civil Engineers, spent much of his career in Florida, where high water tables and frequent hurricanes combine to make a big headache for managers of sanitary sewer systems and residents.

Infiltration and inflow is a common enough problem that it has a shorthand label in the industry -- I & I.

"You can try to control it, but it's almost impossible to create a system that won't have this problem," Bizier said.

Bizier said there are measures that can reduce infiltration and inflow, though some of them add significant costs.

Every community needs to weigh those costs against the frequency of major rain events and flooding, he said.

For example, Chicago has an extensive system of overflow pipes to relieve pressure on the main sanitary sewer system during heavy rains, but a similar system wouldn't be practical in many parts of the country, Bizier said.

Arthur said he's not sure such a system would have been much help in Boulder during the recent floods. Water would have filled the overflow pipes and then the same problems would have occurred.

"The water table was above ground," noted Mike Banuelos, city spokesman for public works.

Utility managers can also install watertight manhole covers, and homeowners can install valves to prevent backflow where their lines connect to the main.

However, those valves require ongoing maintenance, and many homeowners have a hard time remembering to do that, Bizier said.

Arthur said there are some valves allowed in the city code, and interested homeowners should check with a plumber about what might be appropriate in their situation.

The city already has some secured manhole covers, and Arthur said the utility department would continue to look at where they were appropriate.

However, as unpleasant as it was for homeowners, the fact that the system had a way to relieve pressure helped preserve its integrity. If all that water in the system had nowhere to go, it might have started to break apart pipes, Arthur said.

That would have meant much more expensive and time-consuming repairs for the city now and many more parts of the city still without sewer service, Arthur said.

"There's a balancing act," he said.

The most basic thing that wastewater utilities can do to prevent water getting into the system is line older sewer pipes, Bizier said.

Boulder already spends $500,000 a year to line older sewer pipes.

"The more of that we line, the less (infiltration) is an issue," Arthur said.

Arthur said there probably should be a discussion about whether the community wants to spend more to speed up that work.

'We're going to fight them tooth and nail'

Burgess said the city spent decades creating the flood mitigation system that prevented more widespread devastation during the flooding. The sewer infrastructure deserves similar longterm thinking, he said, and he said he would be willing to pay higher rates if that's what it takes to pay for infrastructure upgrades.

Burgess' homeowners insurance paid to cover his sewer backup, but many property owners whose policies include backup coverage haven't been so lucky.

Cory Robinson said he's challenging the denial of a claim to a rental property he owns with his wife and a partner, attorney Jeff Gard, near Inca Parkway and Baseline Road.

Two of the units have significant damage from sewer backups, but the insurance company denied the claim because Robinson doesn't have flood insurance.

"We think it's bad faith on their part, and we're going to fight them tooth and nail," Robinson said. "Our position is that once it enters the sewer line, it's sewage."

Vincent Plymell, a spokesman for the state Division of Insurance, said any property owners with sewer backup coverage whose claim is denied due to the flood should get in touch with the division at 303-894-7490.

The answer will vary depending on the policy, but consumers should go into negotiations with their insurance company armed with correct information.

"That's what we exist for," he said. "We regulate the insurance industry to make sure people get what they pay for in their policy. The answer isn't always in the consumer's favor, but we would always rather people ask the question. Information can help a consumer be their own best advocate."

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